Recorders – Markers and/or driving means therefor – With ink supply to marker
Reexamination Certificate
1999-01-11
2001-07-03
Barlow, John (Department: 2853)
Recorders
Markers and/or driving means therefor
With ink supply to marker
C347S048000, C347S069000
Reexamination Certificate
active
06256050
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a printer which forms an image on a recording medium with ink.
Conventionally, an ink jet printer is known in the art. The known ink jet printer is constructed to propel ink through a nozzle toward a recording medium such as paper. A gap is provided between the nozzle and the recording medium, so that ink passes through the air to the recording medium.
Due to the existence of the gap between the nozzle and the recording medium, the propelled ink tends to spread when the ink reaches to the recording medium. Thus, in order to obtain an image of high resolution, it is necessary to provide a nozzle having small diameter. However, machining of such a nozzle is not easy.
Further, in order to enhance the printing speed of the ink jet printer, it is preferable to provide a line head including an array of the nozzles. However, if a lot of nozzles are assembled as one array, the structure of the line head may be complicated.
SUMMARY OF THE INVENTION
The present invention provides a simple ink transfer printer capable of printing image of high resolution, and capable of printing an image at a high speed.
According to an aspect of the present invention, there is provided an ink transfer printer including (1) a thermal head including at least an array of heating elements, (2) a film with through-holes facing the heating elements, (3) an ink space formed between the thermal head and the film, and (4) a contact mechanism which brings a recording medium in contact with the film. When the heating element generates heat, the ink is transmitted through the through-hole of the film and is transferred to the recording medium. An ink amount controller is provided in the ink space, which controls the amount of ink transmitted through the through-hole to the recording medium.
With such an arrangement, since the amount of ink transmitted to the recording medium can be controlled, a dot size formed on the recording medium can be precisely controlled. Thus, a density of an image can be controlled. It is advantageous in obtaining an image of high resolution. Further, due to the array of the heating elements and their corresponding through-holes, ‘line image’ can be printed on the recording medium. Thus, by feeding the recording medium perpendicular to the line image, a two-dimensional image can be formed at a high speed.
In a particular arrangement, the ink amount controller includes a capacity changer which is arranged to change a capacity of the ink space. As the capacity of the ink space is larger, the amount of ink transmitted to the recording medium increases. Alternatively, as the capacity of the ink space oscillates (that is, increases and decreases in short cycles), it increases the flowability of the ink, so that the amount of ink transmitted to the recording medium may increase.
In a further development, the capacity changer includes at least one piezoelectric element. As the dimension (such as a thickness) of the heating element changes, the capacity of the ink space also changes.
It is preferred that the capacity changer includes a plurality of piezoelectric elements, which are arranged along the array of the heating elements of the thermal heads. It is preferred that each of the piezoelectric elements surrounds one heating element. With this configuration, the amount of the ink activated by each heating element is individually controlled. With this configuration, a dot density can be individually controlled. That is, a gradation control is enabled.
In another particular arrangement, the capacity changer decreases the capacity of the ink space as the temperature of the thermal head increases. With such an arrangement, even if the temperature of the thermal head increases and the viscosity of the ink decreases (e.g., after continued use), the amount of the ink transmitted to the recording medium is kept constant (since the capacity of the ink space decreases). It is advantageous in obtaining the image of high resolution.
The capacity changer includes a heat-sensitive member such as bimetal and shape memory alloy. A plurality of heat-sensitive members are arranged along the array of the heating elements of the thermal heads.
In a further development, the ink transfer printer further includes an ink container which supplies ink to the ink space. In such case, the ink amount controller includes an ink supply regulator which changes an amount of ink supplied to the ink space from the ink tank. As the amount of the ink supplied to the ink space increases, the amount of the ink transmitted to the recording medium increases. Alternatively, as the capacity of the ink space oscillates, it increases the flowability of the ink, so that the amount of ink transmitted to the recording medium may increase. By actively controlling the amount of ink supplied to the ink space, the density of the image can be controlled. Optionally, it is preferred that the amount of ink supplied to the ink space decreases as the temperature of the thermal head increases. With this configuration, the amount of the ink transmitted to the recording medium is kept constant, even if the viscosity of the ink decreases (after continued use). It is advantageous in obtaining the image of high resolution.
In a preferred embodiment, the ink supply regulator is provided in the vicinity of an inlet port of ink through which ink is supplied to the ink space. Further, the ink supply regulator deforms so as to change an area through which ink supplied from the inlet port flows in the ink space. The ink supply regulator includes at least one piezoelectric element, or at least one heat-sensitive member such as bimetal.
REFERENCES:
patent: 3946398 (1976-03-01), Kyser et al.
patent: 4561789 (1985-12-01), Saito
patent: 4731621 (1988-03-01), Hayamizu et al.
patent: 5956066 (1999-09-01), Suzuki
patent: 53-12138 (1978-04-01), None
Horie Mikio
Iwayama Takemi
Orita Hiroshi
Sasaki Masahiko
Suzuki Katsuyoshi
Asahi Kogaku Kogyo Kabushiki Kaisha
Barlow John
Greenblum & Berstein P.L.C.
Mouttet Blaise
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